1. Field of the Invention
The invention relates to charge-coupled-devices (CCD's) and related devices such as imagers with arrays of photodiodes or photoconductors, charge-injection-devices (CID's) and charge-transfer-devices (CTD's).
2. Prior Art
CCD's fill a special need in the computer field due to their unique combination of memory density, access time and cost. When used in their digital mode they require essentially only one simple electrode per bit and very little processing of the substrate to provide excellent dynamic shift registers. In their analog mode they occupy an even more unique position. They have become indispensible in the field of electronic imaging where they are used extensively in hand-held TV type image cameras. In this mode they are known as bucket-brigade devices and require somewhat more sophisticated processing to preserve the relative integrity of the charge packets. In either mode they provide precise delay lines in clocked circuitry having a sufficiently high clock frequency. Examples of the devices, mentioned above, are found in the "ELECTRONICS ENGINEERS' HANDBOOK", 2nd ed., by Fink and Christiansen, copyright 1982, the "ENCYCLOPEDIA OF SCIENCE AND TECHNOLOGY," published by McGraw-Hill, Copyright 1982 and "ADVANCES IN ELECTRONICS AND ELECTRON PHYSICS", Sequin, C. H., and M. F. Tompsett.
The format of CCD's and similar devices make them extremely useful in processing the data they store. Each packet represents a bit in the digital mode or a pixel in the analog mode, each of which can be processed separately; if desired. When this signal processing involves a number of steps, it often becomes necessary to transfer the packets to another CCD to make additional chip real estate available for processing circuits or to avoid interference with the flow of data. An object of the present invention is to provide a unique and extremely useful structure on a single chip that provides such a transfer in the fastest possible mode.